1. Field of the Invention
The invention relates to measurement of motion, more particularly to a method and an apparatus for measuring periodic motion.
2. Description of the Related Art
Many current electronic products, such as a pedometer provided with an accelerometer or a mobile phone provided with the accelerometer in combination with a mobile phone application program, can count a number of steps a user takes. Alternatively, the accelerometer has been arranged on a watch for calculating swimming stroke count.
A conventional technique associated with the accelerometer is to perform signal analysis in the frequency domain, to design filters having a distinct threshold parameters. However, for different kinds of exercises relating to divergent body movements, such as swinging, shaking or rotating, a corresponding filter or algorithm is required to be redesigned for accurate measurement of the body movements. Moreover, some algorithms are required to be modified for setting threshold parameters in different situation. Therefore, how to design a counter suitable for use in different kinds of exercises has always been an important issue in the industry.